Embed iframe feature produces a small window

I am trying to embed a video and/or code snippet using iframe. However, even if i scale to 100. percent it renders fairly small-takes up small section of the question window. There is lots of whit e space available. However, it doesn’t render the same width the answers do. Does this make sense?

Other features I would like to see: one question per page view, and ability to copy/paste images as opposed to uploading image files. Thanks